The present embodiments relate to a method and apparatus for measuring cooling water in a gradient coil of an imaging system.
Magnetic resonance devices for examining objects or patients using magnetic resonance tomography are known, for example, from DE 10 314 215 B4.
Modern magnetic resonance systems (MRT) operate with coils to transmit high-frequency pulses for the nuclear resonance excitation and/or receiving of induced magnetic resonance signals. A magnetic resonance system may include a permanent magnet or (more frequently) a superconducting coil to generate an approximately homogenous basic magnetic field (H0) in an examination region, a large whole body coil (e.g., a body coil or BC) that may be integrated in a fixed manner in the MR device, and a number of small local coils (e.g., surface coils or LC). To read out information, from which images of a patient may be generated, selected regions of the object or patient to be examined are scanned using gradient coils for three axes (e.g., X, Y approximately radial to the patient and Z in the longitudinal direction of the patient). Local coding in magnetic resonance tomography may be realized with the aid of a gradient coil arrangement with three independently activatable magnetically orthogonal gradient field coil systems. By superimposing the three freely scalable fields (e.g., in three directions X, Y, Z) the orientation of the coding plane (e.g., gradient field) may be freely selected.
Gradient field coils according to the known prior art are operated with large currents (e.g., up to 1 kA) and major continuous power losses (e.g., approximately 30 kW). The specified nominal gradient amplitude may therefore only be produced, if the characteristics of water cooling correspond to expected values.
The water temperature upstream and downstream of the cooling circuit is measured, and the cooling water flowing from a number of cooling planes is determined. If the characteristics are outside the tolerance range, irreparable damage may occur at the gradient coil.
The prior art involves integrating an indirect volume counter in a chiller cabinet (e.g., a turbine throughflow meter). Contactless flow sensors (e.g., ultrasound or induction) have also been used.